Oscillator tube



`lune 8, 1937. 1 RQGAN 2,083,241

OSCILLATOR TUBE Filed Sept. 23, 1953 Patented June 8, 1937I U'NITED STATES PATENT rorifice OSCILLATOR TUBE John J. Rogan, Brooklyn, N. Y., assignor to Hy'- grade Sylvania Corporation, Salem, Mass., a i corporation of Massachusetts ApplicationSeptember 23, 1933, SerialNo. 690,665

2 Claims.

I5 the anode itself serves-as a circuit inductance.

A. still further feature relates toa-tube suitable. for use in generatingswaves of' very yshort wavelength. f l f V 'f Other features and advantages not specifically QD enumerated will be apparent after a consideration of" the following detailed description and the appendedclaims.v 1 f Y' Referring to the drawing, Fig. 1 is a schematic circuit diagram showing an oscillation system 25 employing features of the invention;l

Fig- 2 represents a modification' of the system of Fig. 1; 'Y l Fig. 3 represents a further modification ofthe system of Fig.v 1; and Y 2O Fig. 4 represents a'fstructure of tube vthat may be .employed in the system of Fig. 3. 1 t

Referring: more `particularly to Fig. 1',v the numeral l indicates `an enclosing envelope of glass or other similar-material which is preferably evacuated 'to the point where ionization does not `occur during the normal use of the tube. Suitably mounted within the envelope I is an electron emitting cathode 2 of any suitable type such as a iilamentary cathode, an indirectly heated lo cathode or the like. Cooperating with the cathode 50 as ordinarily employedl inthe manufacture'v of radio tubes-or thelike. For example, the' cathode 2 may beA centrally located with respect to the grid *4. whichv may take-the form of a helically wound wire or a perforated cylinder of metal.

55 Similarly, the anode 3 may be in the form of a cylindrical body surrounding the grid 4, and like- Wise the electrode 5 may be in the form. of a cylinder surrounding the anode 3. Y

Any suitable type of ,input circuit may be employed such as schematically represented in the drawing by the transformer E, Vwhich has its secondary connected across the f grid 4 and the cathode 2, it being understood that if desired, a suitable biasing potential (not shown) may be.

inserted in the input circuit to bias the grid 4 with respect to the cathode 2. Ilj'he output Lof the system4 includes atunedoscillation circuit comprising the primary Al'of an output transformer which is shunted by a tuning condenser 8 inthe manner well known intheradio, art. The tuned oscillation circuit has one terminal connected to the anode 3 and the other terminal connected to vthe cathode 2in series with a suitable source of as indicated. Preferably, the electrode 5 is maintained at ahigher potential than the anode3 for purposes about to be described. Preferably also, the sources fand I Il are shuntedby condensers |ll2 to;by-pass the generated oscillations therearound-.fris indicated rby the numeral l3,-;the

anode 3 is provided on itsfiouter surface ywith aV coating of electron-emissive material or materials, of any well-known composition. The tube is preferablydesigned so that during its normal operation there is suiiicient emission fromy the cathode 2 andat sufcient Velocity to raise the anode3 by electron bombardmentfto a temperature at Which'thecoating l3emits the desired quantity Yof electrons; Heretofore, in the-art it has been the usual practice,-.particularly in kthe case of transmitter tubes,V to maintain the ,anode 3 as cool as possible, Various Vexpedients having been arranged for this purpose such as radiators, water cooling systems, or the like. The present invention, however; i.contemplates thel utilization of the heat of the anode torender the latter emissive preferablyas a'primary emitter', and inorder to render the tube'more stableeven Withfthe'anode operating at high temperature,this anodeshould preferably ,be `of a material, which is substantially :entirely free from occluded or entrapped igases, either on its' surfaceV oron its interior.V 'Ag synthetic graphite anodeprepared in accordance with the disclosure of PatentNo. 1,981,821,- meets these `requirements', and'furthermore such an anode has the capacityof operation at even red heat with- 'out-the liberation of gases within ther envelope.

While' the anode A3 may be raised to emitting ternperature in any known manner, it is preferred, in accordance with this invention, to take advantage of the electron bombardment from the cathode 2. Consequently, sufficient potential should be impressed upon the anode 3 to cause the electrons emitted from the cathode 2 to bombard the said anode 3 with sufficient velocity in order to raise the temperature of said anode to the required degree. If desired, an additional electron accelerating electrode (not shown) may be interposed between the grid 4 and the anode 3. When the tube is operating with the anode 3 at the emitting temperature, the potential of the auxiliary electrode 5 is preferably adjusted so as i to impart to the output circuit a negative re-V This condition can be,

sistance characteristic. attained since electrons arriving at the anode 3 from the cathode 2 tend tobe'neutralized by the i primary electrons emitted from the anode 3 to the auxiliary electrode 5 which, as above stated, is preferably at a higher potential than the anode 3. By a suitable adjustment of the relative potential of the electrodes 3 and with respect to the cathode 2, a condition may be attained wherein an increase of potential on anode 3 will result in a reduction in current in the output circuit, and vice Versa. This negative resistance between the electrodes 3 and 5 may be designed with respect to the electrical constants of the tuned oscillation circuit so as to result in the production of sustained oscillations in this latter circuit.'l These oscillations may, therefore, be impressed on asuitable radiating system such as the antenna I4 or the like.

lIt will be understood, of course, that the system of Fig. 1, while primarily designed for the production of sustained oscillations, by utilizing the primary electron emissions from theV electrode 3, is also suitable for amplification or'detection, by choosing the proper bias of the control grid 4 with respect to the cathode 2. Furthermore, the system of Fig. 1 may be used as a combined oscillator-modulator by properly biasing the grid 4 and impressing the signals to be transmitted through the transformer 6, resulting in the production in the output circuit of sustained oscillations which are modulated-in accordance with the impressed signals. l

The above described system is therefore capable of generating sustained oscillations without re.- quiring any so-called feed-back betweenthe output circuit and the input circuit, since the oscillatory condition isV controlled entirely by the negative resistance characteristic obtainable by the primary electron emission from anode 3 to the auxiliary electrode 5. In order to prevent any undesired feed-back between the output and input circuits, suitable neutralizing circuits well Yknown in the art may be employed, or, -if desired,

Referring to Fig. 2, there is'shown a system f similarin general to Fig. 1, wherein both the innerand outer faces of the anode 3 are provided with emissive coatings. In this embodiment, the auxiliary electrode 5 completely surrounds the anode 3, bothl as regards the interior as well as the exterior surfaces of the said anode, Vso as to utilize the primary emission from both" surfaces of the anode. vHere again the tube Iis preferably designed so that during its normal operation as an oscillator, the anode is at an emitting temperature, and advantage is taken of the normal bombardment of the anode from the cathode to produce primary emission from the said anode to the auxiliary electrode 5. By suitable adjustment of the relative potentials of the anodes 3 and 5 with respect to the cathode 2, the output circuit may be given any desired positive or negative characteristic and therefore the system of Fig. 2, like that of Fig. 1, may be used for oscillation, amplification, detection or modulation.

Referring to Fig. 3, there is shown a modification of the system of Figs. 1 and 2, wherein the main output anode is in the form of a coil I5 having the turns` thereof freely spaced from each other so as to form in itself an electrical inductance. The auxiliary electrode 5, instead of being positioned exteriorly of the anode I5, is positioned between the control grid 4 and said anode I5. As indicated in Fig. 3, the electrode 5 is maintained at a higher potential than the anode I5 so that electrons, whether primary or second- 'l ary, from the anode I5, are attracted by the auxiliary electrode 5. If thetube I is to utilize only the secondary emission from the anode, then this anode may consist of bare Wire such as molybdenuin or the like, and the tube may be designed so that the said anode operates at less than the primary emission temperature. Due to the acceleration ofthe electrons from the cathode 2, these electrons pass through the openings in the electrode 5 and; striking the anode I5, result in the emission of secondary electrons from said anode. By properly proportioning the potentials and spacings of the electrodes 5 and I5, the output circuit lcomprisingthe inductance anode I5 and the condenser I6 may be given a negative resistance characteristic, and oscillations may therefore be produced in the said output circuit. Since the inductance anode I5 is included serially in the output circuit, the oscillatory currents therefore pass through the turnsy of the said inductance anode, and advantage may be taken of this current to renderthe anode I5 effective as a primary emitter, in which event the said anode I5 is preferably coated With electron emissive material or materials.

Referring to Fig. 4, there isshown a form of tube that may be used in the system of Fig. 3. In this figure the tube envelope is indicated by the line, and sealed to said envelope in the usual manner is a press I'I into which are sealed the various electrode support and lead-in wires. While Fig. V4 shows an indirectly heated cathode 2, it will be understood that anyother type of cathode may be employed. The lead-in Wires for the cathode heater filament are designated by the numerals I8, I9. Surrounding the cathode 2 is a grid 4 in the form of a helically Wound Wire having the turns thereof attached to support wires 20, 2|. Surrounding the grid 4 is the foraminous electrode 5 of woven wire, mesh fabric, etc., a1- though any other foraminous structure may be employed. 'I'his electrode 5 is-provided with appropriate support wires 22, 23. Surrounding the electrode 5 isthe coiled anode I5 having the, turns thereofA freely spaced from one another so as to provide an electrical inductance. The uppermost turn of the anode is connected to a support and lead-in wire 24, while the lowermost turn ofthe anode is connected to the lead-in wire 25. Thus the output current is enabled to flow seriallythrough the individual turns of the anode inductance I5 for purposes described above in connection-with Fig. 3. If desired, the anode I 5 maybe coated with electron-emissive material.

If desired,the grid electrode 4 may likewise be Wound with its turns freely spaced so as to provide an input inductance, and preferably, ther circuit connections are such that the feed-back inductance effect of the anode I5 is in degenerative relation with respect to the inductance eiect of the grid 4, so as to neutralize or prevent regenerative feed-back from the output to the input circuits.

While specific embodiments have been described herein, it will be understood that the invention is not limited thereto, but is capable of use in any tube for the production of oscillations by utilizing primary emission from the main or output anode.

Various changes and modifications may therefore be made without departing from the spirit and scope of the invention.

What I claim is:

1. An oscillator tube comprising an evacuated envelope, a cathode for emitting primary electrons, an anode for receiving the electrons from said cathode, a control electrode between said cathode and said anode, said control electrode controlling the number of primary electrons from Y said cathode reaching said anode, said anode having a coating of electron-emissive material on the side of said anode facing said control grid and being the output anode of the tube.

2. An oscillator tube comprising an evacuated envelope, an electron emitting cathode, an anode for said cathode, said anode having a coating of electron-emissive material thereon to act as a primary emitter under bombardment of the elec. trons from said cathode, and another electrode to act as an anode to the first-mentioned anode and having portions disposed on opposite sides of said rst-mentioned anode, said first-mentioned anode having said coating of electronemissive material on both sides thereof.

JOHN J. ROGAN. 

